Davey Jones' Locker = the bottom of the ocean! (and yes, we spell "Davey" with an "e," thank you very much!)

"Was there a real Davey Jones? That's a question linguists have
pondered since 18th-century sailors started using the name for
the evil spirit of the sea or the deadly depths of the ocean.
Some claim the original Davey Jones was a British pirate, but
there's no evidence such a person actually existed. Others swear
he was a London pub owner who kept drugged ale in a special
locker, served it to the unwary, then had them shanghaied to sea.
But the theory considered most plausible is that the "Davey" in
"Davey Jones' Locker" was inspired by St. David, the patron saint
of Wales, who was often invoked by Welsh sailors. The "Jones" is
traced to Jonah, the Biblical figure who was swallowed by a
whale."